Eshghpour 2014.

Study characteristics
Methods	Study design: double‐blinded, randomised clinical trial, split‐mouth technique Conducted in: Iran
Participants	Inclusion criteria: 18 to 35 years of age, have American Society of Anesthesiologists physical status I or II; have bilateral mandibular third molars; have the same difficulty level of bilateral third molars based on the Pederson classification Exclusion criteria: pericoronitis of the mandibular third molar(s), received antibiotic regimen during the previous 2 weeks, had a smoking habit, was lactating or pregnant, was using oral contraceptives, had any lesions found on the panoramic radiograph, had any complications during extractions, or had received more than 2 anaesthetic cartridges during surgery Number randomised: 85 Number evaluated: 78 (bilateral impacted teeth) (33 male and 45 female; mean age 25.09 years)
Interventions	Comparison: placement of PRF versus none in the extracted socket PRF was placed in 1 of the sockets, and the other socket received no treatment. Group A intervention (n = 78) Group B control (n = 78) Note: postoperative prescriptions were amoxicillin (500 mg 3 times daily, n = 21) and paracetamol (500 mg 3 times daily, for a maximum of 3 days)
Outcomes	Alveolar osteitis at days 2 and 7 Based on the c2 analysis, the frequency of alveolar osteitis had a significant association with the application of PRF. Sockets that received PRF after extraction had a statistically significant decreased risk of developing alveolar osteitis compared with non‐PRF sockets (risk ratio 0.44, 95% confidence interval 0.148 to 0.989; P = 0.042).
Notes	Descriptive statistics (frequency, mean, and standard deviation) were determined for each variable. Data analysis was performed with c2 and t tests using SPSS 11.5 (SPSS Inc, Chicago, IL), with a confidence interval of 95%. Sample size calculation: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "PRF was randomly inserted into one of the sockets" Comment: coin toss technique was used to decide which side received intervention or control
Allocation concealment (selection bias)	Unclear risk	Comment: not clear whether randomisation of participants was done by someone different from the person who recruited participants
Blinding (performance bias and detection bias) patient	Unclear risk	Quote: an operator blinded to the surgery performed the PRF insertion and suturing. Hence, the participants and the surgeon were blind to the side in which PRF had been inserted. Comment: all participants had blood taken and PRF placed. However, a new surgeon coming in to work on one side of the mouth would reveal which side the PRF went into.
Blinding (performance bias and detection bias) assessor	Low risk	Quote: "the randomisation data were kept unknown by another investigator until the end of the study"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "eighty‐five patients met the inclusion criteria and entered the study; however, 6 patients received more than 2 anesthetic cartridges and 1 female patient had used oral contraceptives during the first postoperative week (as emergency birth control). Therefore, 78 patients (33 male and 45 female; mean age, 25.09 Æ 4.25 yr) completed the study" Comment: 85 participants were recruited, and the outcomes of 78 were reported. Justification for this was provided.
Selective reporting (reporting bias)	Low risk	Planned outcomes were reported.
Other bias	Low risk	No other sources of bias identified.